1. Technical Field
The present invention relates to a powder metal composition for producing wear resistant and easily machinable valve seat inserts for internal combustion engines, and to the valve seat inserts produced from the composition.
2. Description of the Prior Art
Most internal combustion engine valve seat inserts are made by a powder metal process. A powder metal process is suitable for valve seat insert production because the process is capable of forming the valve seat insert to near its final shape. Some machining is required, but the powder metal process reduces machining requirements, making the production of the valve seat inserts economical.
Powder metal compositions for producing valve seat inserts having both good wear resistance and machinability are known. However, such compositions generally require a high percentage of alloying, or costly processing, both requirements adding to the cost of the inserts.
U.S. Pat. No. 3,806,325 discloses an iron based alloy for a valve seat ring for an internal combustion engine. One alloy disclosed in the patent is obtained by blending iron powder with about 0.25 to 8 weight percent molybdenum, 0.1 to 1 weight percent carbon, and 1 to 20 weight percent nickel and/or copper. The powder mixture is formed and sintered to a density of about 6.7 grams per cm.sup.3 and then is infiltrated with an infiltrating material such as lead.